Pumping apparatus



P 3, 1940- M. 5. JENNINGS 2,213,248

PUMPING APPARATUS Filed March 4, 1937 5 Sheets-Sheet).

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Sept. 3, 1 M. E. JENNINGS PUMPING APPARATUS 3 Sheets-Sheet 3 Filed March 4, 1937 Patented Sept, 3, 1

PUWHNG APPARATUS Marshall E. Jennings, Michigan City, Ind, assignor to Sullivan Machinery Company, a corporation of Massachusetts Application March a, 1937, Serial No. 128,903

28 Claims. (01. 230-24) My invention relates to pumping apparatus, charge valve, where the presssure on the seat and, more particularly, to unloading means for surface of the valve corresponds in the open posipumping apparatus. tion of the valve to discharge pressure, a mere In the unloading of pumping apparatus, and venting of the pressure from the back of the 5 particularly in the unloading of air compressors, valve, at the face of the guard, will produce such 5 it is important that there be provided means a diiferentialin pressure as to maintain the which shall be positive in operation, quick in valve automatically in open position. Myinvenaction, simple in construction, and not subject to tion contemplates, therefore, the employment, easy derangement. It is also important that the for the maintaining in unloading position of unloading devices, particularly any which are to either inlet or discharge valves, of pressure dif- I 10 be associated with the valve mechanisms of the ferences between the face of the valve adjacent pumping apparatus, shall be very simple. Dethe guard and the face of the valve towards the vices for opening and holding open the inlet seat, however produced. valves of compressors to effect unloading are very It is an object of my invention to provide an common. Devices for effecting unloading by inimproved pump unloading apparatus. It is an- 5 ter-connecting the opposite ends of the cylinother object of my invention to provide an imders through the discharge connection of the proved apparatus for effecting unloading which pumping apparatus may also be used. With inshall maintain in unloading-effecting position let valve opening unloading devices, interference one of the valve devices of a pump, by means go with flow of air to the inlet ports is frequently for subjecting the side thereof remote from its a difliculty, and substantial complication in seat to a pressure lower than the pressure which structure at times results. To effect opening prevails in the passage through which it controls and maintaining open of discharge valves preflow. It is a further object of my invention to sents a substantial problem. If a device or sysprovide an improved apparatus for efiecting un- 2.1 tem can be devised for opening and maintainloading which shall cooperate with the inlet ing open either inlet valves or discharge valves valve or valves of a pump, and, with a minimum a pumping apparatus avoiding the complications interference with the air flow through the inlet and interferences with flow usually attending the ports, yet he certainly efiective and maintain use of inlet valve opening types of unloading apthe valves open without risk of fluttering. It is paratussuch a device or system would present another object of my invention to provide an 30 a. marked advantage; and I have devised a. sysimproved vacuum-operated unloading means. tem which, in its "broad aspects, is applicable It is still another object of my invention to proeither to hold open an inlet valve or a plurality vide an improved apparatus for efiecting unloadof inlet valves, or a discharge valve or a plurality ing, which shall cooperate with the discharge of discharge valves, thereby to effect unloading valve or valves of a pump while in no material with an absolute minimum of interference with way reducing the space for free discharge of fluid freedom of flow of air relative to the pumping past the valve when the latter is in open position. apparatus cylinder, and of great simplicity and It is a further object of my invention to provide effectiveness. an improved unloading means made effective by 40 From one broad aspect of my invention, the a pressure less than the-pressure whose flow is 40 same may be embodied either in conjunction controlled by the valve controlled by said unloadwith an inlet valve or in conjunction with a dising means. It is a still further object of my charge valve, and may include means associated invention to provide an improved compressor with the guard of the valve mechanism with discharge pressure responsive system for effectwhich it is incorporated for producing a lower ing unloading of a compressor, in which the I pressure at the face of the guard which checks actual valve holding forces shall be the result the opening movement of the valve than prevails of the subjecting of the valve to a vacuum. It at the opposite or seating side of the valve when is yet another object of my invention to provide, the latter is in open position. In the case of an an improved apparatus for efi'ecting compressor inlet valve for a single stage compressor, where unloading according to which the valve element 50 the pressure acting upon the seat side of the to be controlled is subjected directlyto apressure valve is atmospheric or substantially atmospheric less than that'which it controls, to bring about in the open position of the valve, the provision of unloading, with a result that great simplification a vacuum in the guard will result in a very effecof construction is possible. Still another object tive unloading operation. In the case of a disof my invention is to provide a vacuum-operated 55 unloading device for holding in open position a pump unloading valve, holding said valve in such position during unloading that the same shall in no way interfere with or be subjected to any material closing force as a result of the flow of air through the inlet ports of the pumping apparatus of which said valve forms a part. Yet a further object is to provide unloading means associated with a discharge valve for a pump, of simple construction yet efiective to relieve the valve when in unloading position from any closing tendency resulting from flow, in either direction pastthe same, of fluid moving towards and from the cylinder with which said valve is associated. Other objects and advantages of my invention will hereinafter more fully appear.

In the accompanying drawings, in which three illustrative embodiments of my invention have been shown,

Fig. 1 is a view partially in side elevation and partially in central vertical section through a single stage compressor in conjunction with which my invention is incorporated.

Fig. 2 is an enlarged detail section on a plane corresponding to the plane of Fig. 1. through an inlet and discharge valve mechanism at one end of a pump cylinder such as is shown in Fig. 1.

Fig. 3 is a face view of a valve guard used in the practice of my invention.

Fig. 4 is an enlarged fragmentary section on the plane of the line 4-4 of Fig. 3.

Fig. 5 is a fragmentary view showing portions of the inlet valve structure of Fig. 2, showing the parts in unloading condition.

Fig. 6 is a sectional view through a controlling valve forming a portion of the illustrative embodiment of the invention.

Fig. 7 is a view on an enlarged scale showing portions of the structure shown in Fig. 1, but in elevation, as it were, showing a piping and valve layout of the unloading mechanism of Fig. 1.

Fig. 8 is a view, partially in section and-partlally diagrammatic, with parts on different scales, illustrating an embodiment of my invention in which the same is incorporated in the control of a pump discharge valve.

Fig. 9 shows a modified construction in which the invention is incorporated, in an illustrative embodiment, in .a compound compresson,

From the foregoing statements it will be evident that my invention is capable, in difierent aspects, of incorporation in single-stagev and in multi-stage pumping apparatus, in conjunction with inlet valves, or in conjunction with discharge valves. In Figs. 1 to 7 an embodiment in a'single-stage double-acting compressor, in association with the inlet. valves thereof, is shown. In Fig. 8 an embodiment in conjunction with one end 01 a pump cylinder, in con-. junction with a discharge valve of that cylinder end, will be observed. In Fig. 9 an embodiment in a compound or two-stage pumping apparatus is disclosed.

Referring. first to Figs. 1 to 7 inclusive, it will be observed that .an air compressor I having a driving pulley and fly wheel 2 supported upon a crank shaft 3 is provided with a piston 4 reciprocable in a cylinder 5 which comprises a central cylinder member 6 having a liner 1 and head and crank end cylinder heads 8 and 9 respectively. The compressor takes in air through an intake connection H] which communicates with a passage H in the cylinder member 6, and.

with end intake chambers l2, l2, one in each of the heads 8 and 9. Inlet valve mechanism, of

which one is shown at each end of the cylinder, are generally designated l3; and discharge valve mechanisms, generally designated l4, control the discharge of air from the cylinder to a common discharge passage |5 from which the air is delivered through a pipe I6 to a point of use or storage, herein represented by a receiver Referring now to Fig. 2, it will be noted that the discharge valve mechanism l4 includes a seat element 20, to which there is suitably secured a guard member 2|; and a valve 22 normally seats upon a seat 23 and controls the flow of fluid through passages 24 from the cylinder bore to the discharge space IS. A spring 25 normally holds the valve seated, and the valve and spring are guided by suitable guiding means 26. The discharge valve assembly is held in position by a stud 28 and a nut 29.

The inlet valve mechanism will be observed to be very similar in general appearance to conventional inlet valve mechanisms, and only by comparatively close inspection are its radical differences from the conventional inlet valve to be noted. It is held in position as a whole by a nut 30, threadedly engaging a reduced extension 3| of the stud 28, and comprises a seat element 32, a guard element 33, a guide element 34, an annular valve 35, and a spring 36 of the bowed or wave type, the several parts being held together by suitable machine screws or the like 31.

The guard 33 is somewhat thicker thanthe usual guard of this type, butthis is simply an added advantage, for it tends to reduce the clearance volume of the cylinder. Referring first to Fig. 3, it may be observed that the side of the guard plate 33 towards the valve seat is provided with a series of grooves of progressively increasing depth and diminishing width. First there is a groove 40 of a radial width such as smoothly to receive the valve element 35. Next there is a slightly deeper groove 4| in which a vacuum is produced and maintained during unloading. Finally, there is a still deeper groove 42 which positions the seating spring 36, as will be noted in Fig. 2. The valve guard is provided with a ra dially extending passage 44 which communicates through passages 45 and 46 with the bottom of the groove 4| .at opposite sides of the recess or groove 42 which serves to position and.

center the spring 36. The outer end of the radially extending passage is sealed, as at 41, while its inner end communicates with a port 48 in a conducting element 49, which takes the place oi. one of the screws 31, which act to hold the parts of the apparatus together. Now it' will be evident, when it is noted that the depth of the groove 40 is suflicient toallow the valve element 35, when it is seated upon the annular surfaces 50 and 50 at the bottom of the groove 40, to be disposed wholly within the solid annulus, so-tospeak, of the guard member 33, that there will be no possibility of the flow between the space |2 and the cylinder bore effecting any tendency toclose the valve 35. It will be noted that the that a vacuum pump 52 of anyfsuitableliorm is ,driven, herein by a belt 53, from a pulley 54 on .the crank shaft 3. The vacuum pump draws the air'irom a line 55, and the vacuum line 55 is connected by branch connections 56 and 51'to approximately the central points in control valve devices, designated 58-one of which is associated .--witheach of the inlet valve mechanisms I3.

Each mechanism 58 includes a central body portion 59 and a lower end portion 60, between which a diaphragm BI is clamped. The central portion 59 has a bore 62 with which, between its ends, the connection 56 communicates. A valve element 63 is secured as at 64 to the diaphragm 6I, and is adapted, in the position shown in'Fig. 6, to shut ofi communication between the connection 56 and a connection 65 which is connected in any suitable way with the passage 64, heretofore mentioned. The valve mechanism 58 also includes an upper head 66; and this up per head of the valve mechanism 58 has an annular seat 61 through which a passage opens, leading to a vacuum breaker valve 68, which permits' ingress of air but prevents its discharge. The valve 63 has connected to it, or formed integral with it, a head 69 which is adapted either to engage the seat 61 and prevent communication between the vacuum breaking connection and the connection 65, or to seat upon another seat surrounding the upper end of the bore inwhich the valve 63 moves and cut oif the comthe force exerted by the spring H and the force exerted by the pressure upon valve 63 tending to hold it in the position of Fig. 6, to move the valve 63 to its opposite position with its head 69 engaging seat 61. Now referring to Figs. 1 and 7, it will be noted that a connection leads from the receiver or compressor discharge line to a pilot valve 16, which may be of any usual or well known form, and which is operativeto admit pressure to a line 11, when the compressor discharge pressure reaches a desired uppervalue, and to vent the pressure from the line .11 when the compressor discharge pressure falls off to a desired minimum value. The pilot valve shownat 16 is a wellknown valve of commerce, a so-called RCS pilot valve. terminating in the connection 12 of one valve device 58, and branch'll leading to a corresponding connection associated with the other of the control devices 58, herein the one associated with the head-end unloading means.

The mode of operation of the apparatus so far described willbe very easily followed.- Let us assume that the receiver pressure rises to the maximum desired value, and that accordingly the pilot valve 16 acts to admit air through the connection 11 under receiver pressure. This air will act upon.the diaphragms 6| and move the valves 63 to positions in which their heads 69 A suitablespring 1I- normally forces Connection 11' is branched, branch 11 will engage their seats 61 and cut off communication between connections. 65 and theyacuum breaker devices 68, while'establishing communication between the connections 65 and the vacuum line 55 through the connections 56 and 51.

' Accordingly, a vacuum will be immediately produced in each of the grooves 4I associated with the inlet valves; and the inlet valves, upon their opening movements, will move back into the grooves 40 and be held there. .So long as the vacuum is maintained in the grooves 4|, the inlet valves will remain off their seats, in fullopen position, the vacuum produced being more than sufiicient to overcome the pressure of the springs 36. There will be no tendency of the inlet valves to be seated upon rush of air through the ports, as they will be shrouded, as it were, over their entire edge portions by the edges of the vacuum guard, and they will be subjected, moreover, at least to the inlet pressure of the compressor at all times on their seat sides, while subjected to a sub-atmospheric pressure on their other sides. When the receiver pressure has been reduced to the desired minimum value, valve 16 will vent the pressure from the line 11, and so the diaphragms 6| willbe relieved of pressure on their lower sides, and valves 63 will be moved downward again to the position shown in Fig. 6

This will cut oil communication between the a bore 82 and a discharge passage, of which a portion is shown at 83. Stepped bores 84 and 85 are formed in the cylinder head 80 and provide shoulders 86 and 81 against which a discharge valve mechanism 88 and an inlet valve mechanism 89 may be suitably clamped, with an intervening washer if desired, by means of a stud 90 and nuts respectively numbered 9I and 92. The inlet valve mechanism is of a conventional type,

- including a ported seat member 93 having flow passages 94 therein and concentric seats 95 and 96 engaged by an annular valve 91 which is held normally pressedagainst its seat by a spring 98 which also engages a guard 99, all as in a well known valve construction. 'The discharge valve mechanism 88 includes, herein, a conventional ported seat member IOI to which there is suitably secured a guide block I02 and a guard I03 by means of threaded elements, herein machine screws, I04. A conventional annular valve I05 is designed to be held seated normally by a spring I06 of the annular, transversely flexed type. The valve guard I03 is provided with three concentric, progressively narrower, communicating grooves respectively numbered I01, I08 and I99. Groove I09'constitutes a guiding groove for the narrow annular bowed spring I06. Groove I08 is proided to enable free communication completely around the valve, when said valve is seated against the bottom of groove I01, said last men tioned groove being formed of a depth and width I on its suction strokes, it will cause unseating of the valve 01 to take place and the flow of air into the cylinder. On the next succeeding opposite stroke of the piston, the valve I05 will be forced from its seat by the compressed fluid, and will compress its spring I06 and ordinarily enter, at least partially, the groove I01. Upon the next succeeding suction stroke of the piston, the valve I05 will, of course, be seated again, during loaded operation of the pump.

If a pressure less than the discharge pressure of the compressor can be produced in any way .within the groove I08, the discharge valve I05 will remain open, as soon as it once is fully opened, so long as such lowered pressure status remains in the groove I08. With a discharge pressure of '15 or 100 pounds, it will be evident that a pressure not lower than atmospheric, created and maintained in the groove I08 will most effectively bring about and continue unloading, by holding the discharge valve off its seat. No vacuum condition needs to be produced with a device of this character, where the valve opening pressures are considerably above atmospheric.

Accordingly, unloading may be efiected merely by venting to atmosphere the pressure within the groove I08, when desired.

To illustrate one of many suitable devices for eflecting the venting to atmosphere of the groove I08, I have shown a pressure-responsive switch mechanism II I, comprising a diaphragm I I2 subjected through a conduit II3 to compressor discharge pressure. The diaphragm II2 controls a bell-crank lever I I4, which actuates a switch, diagrammatically shown at II5. When the compressor discharge pressure reaches a desired maximum, the diaphragm II2, through the bellcrank lever II4, will open the switch H5. Upon a desired drop in pressure, to a value at which it is desired to effect reloading, the diaphragm I I2 will move to a position permitting recloslng of the switch II I5. Switch II5 controls a circuit including a conductor 6, a source of current 1, a conductor II8, a solenoid H9, and another conductor I20. When the switch is closed, the solenoid H9 is energized. Solenoid H9 controls the position of a plunger I22 which controls the positions of a pair of oppositely facing valves I23 and I24 adapted selectively to cooperate with seats I25 and I26 respectively. When valve I24 is seated, it shuts ofi communication between a chamber I21 connected by a conduit I28 with the groove I08, and a further chamber I30 connected as at I3I to atmosphere. When valve I23 is seated, it cuts off communication between the chamber I21 and a chamber I32, which is connected by a conduit I33 with the discharge space 83 of the compressor. When the solenoid H9 is de-energized, valve'l23 is normally closed and valve I24 normally open. I

The mode of operation of this illustrative construction will be readily followed. In the position of the parts shown, the compressor discharge pressure is at such a value that loaded operation of the compressor is desired. The switch H5 is therefore closed, the solenoid I I9 energized, valve I24 held seated, and valve I23 maintained unseated. Accordingly, the same pressure prevails in the groove I08 that prevails in the discharge space 83 and in the stepped bore 84, and accordingly the valve I05 operates in an entirely normal manner. When the compressor discharge pressure'increases, however, sufliciently to cause the diaphragm II2 to open the switch II5, the solenoid II3 will be de-energized, permitting the plunger I22 to drop down to close the valve I23 and open the valve I24. The pressure in the groove I08 will immediately drop to atmospheric byway of conduit I28, chamber I21, port I28, chamber I30 and atmospheric vent I3I; and the discharge valve I 05 on its first opening movement following the drop of pressure in the groove I 08 will move fully into the groove I01 and be held there until reloading is desired. When the compressor discharge pressure falls ofl sufllciently to cause recloslng of switch II5, the solenoid II9 will be reenergized and valve I23 will reopen and valve I24 reclose, and the pressure in the groove I08 will equalize with that in chamber 83, and

the discharge valve will resume normal functioning. Valves I 23 and I24 may be interconnected, or spring-loaded, to insure seating when desired.

In the embodiment of the invention shown in Fig. 9 there is simply provided an adaptation of the system of unloading shown in Figs. 1 to 7 to a compound compressor. Here it will be noted that a common pilot valve I6 responsive through a connection I5 to the pressure in the receiver I'I' controls through one branch I40 of a forked connection I 40 the flow to the valve devices 58, 58 associated with the high pressure cylinder I of the compound compressor I, while a branch I40 of the forked connection I40 leads to the valve devices 58", 58 controlling the unloading of the opposite ends of the low pressure cylinder I42 of the compound compressor I. In so far as the apparatus associated with the low pressure cylinder is concerned, there is no essential difference from the apparatus shown in Figs. 1 to '7, a vacuum connection 55 being provided with a lowpressure-cylinder branch 55 for producing a vacuum for use in unloading the low pressure cylinder through its inlet valves. The other branch, 55 of the vacuum connection leads to the devices 58, 58 associated with the high pressure system. A delay in the unloading of the high pressure cylinder is effected by employing a wellknown arrangement, using a delay tank D with a suitably restricted flow line I43 limiting rate of flow through the delay tank to the devices 58", 58 and a check valve I44 permitting rapid bleeding when reloading is desired. Checkvalved connections 88' lead to the intercooler, instead of to the atmosphere, in the case of the high pressure devices 58'.

Detailed description of the mode of operation of this embodiment is unnecessary, as the low pressure cylinder unloading devices operate the same as the devices of Figs. l to 7, while'the high pressure cylinder unloading devices are simply made effective subsequent to the low pressure cylinder ones by the apparatus described, so that the intercooler pressure will be pumped down be fore complete unloading occurs.

It will be obvious that I have provided a very effective arrangement according to which a vacuum, or a pressure less than that which the valve controls, may be applied in a very convenient manner to effect compressor unloading, and may be applied to an inlet valve mechanism or to a discharge valve mechanism which will be little different in appearance and little more complicated than the ordinary construction without unloading means. It 'will be evident that the arrangement is simple, and certain in action, and that when unloading has been effected there is no tendency during the passage 0. fluid back and forth between the cylinder bore and the space continuously placed in communication therewith for any fluid seating-pressures to act upon the valves.

upon the relative movements between said ele-- While there are in this application specifically described three embodiments which my invention may assume in practice, it will be understood that these are shown for purposes of illustration and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What .I claim as new and desire to secure by Letters Patent is:

1. In a pump controlling system, a valve seat, a valve cooperating with said seat and movable to open position by a pressure-differential created during each cycle of loaded pump operation, and unloading means associated with said valve for subjecting its side more remote from said seat to a pressure less than the pressure which opens said valve to hold said valve open continuously, thereby to effect unloading.

2. In a pump controlling system, a cylinder, a

piston, and valve mechanism including an inletvalve mechanism including a valve seat, a valve cooperating therewith and opened automatically by the pressure differential created on suction strokesof said piston during loaded pump operation, and unloading means associated with said valve for subjecting the side thereof remote from its seat to a vacuum to maintain said valve open during the discharge strokes of said piston.

3. In a pump controlling system, a cylinder, a

piston, and valve mechanism including a discharge valve mechanism including a valve seat, a valve cooperating therewith and opened automatically by the pressure differential created on discharge strokes of said piston, and unloading means associated with said valve for subjecting the side thereof remote from its seat to less than discharge pressure to maintain said valve open during the suction strokes of said piston.

4. In combination, relatively movable pump elements cooperating to provide a pump chammore remote from said pump chamber, through-' out theentire cycle of relative movements between said pump elements, to a pressure less than the pressure within said pump chamber, to hold said valve device open.

5. In combination, relatively movable pump elements cooperating to provide apump chamber, valve devices associated with said pump chamber and automatically controlled during pumping by the. pressure variations produced upon the relative movements between said elements and respectively serving as inlet and discharge control means for said chamber, and un-- loading means including means for subjecting one of said valve devices, upon the side thereof which, when said valve device is closed, is nearer said pump chamber, throughout the entire cycle of relative movements between said pump elements, to a pressure less than the pump intake pressure, to hold said valve device open. I

6. In combination, relatively movable pump elements cooperating to provide a pump chamber, valve devices associated with said pump chamber and automatically controlled during pumping by the pressure variations produced ments and respectively serving as inlet and dischargecontrol means for said chamber and each having a seat towards and from which it is movable during opening and closing, and unloading.

means including means for subjecting one of said valve devices, upon the side thereof more remote from its seat, throughout the entire cycle of relative movements between said pump elements, to

' a pressure lessthan that at its other side, to hold and unloading means associated with each of said valves for subjecting the side thereof remote from its seat to a vacuum to maintain the same open to efiect unloading. v

8. In combination, a compound compressor having a high pressure cylinder and a low pressure cylinder, each having a piston, and inlet and discharge valve mechanisms for said cylinders,

said inlet valve mechanisms each including a valve seat, a valve cooperating therewith and opened auomatically by the pressure difierentials created by piston movement in the cylinder which it serves during'loacledoperation, and unloading means associated with each of said valves for subjecting the side thereof remote from its seat to a pressure enough lower than that at its opposite side to maintain it open throughout both of the opposite piston strokes, to eflect unloading.

9. In combination, a compound compressor having a high pressure cylinder and a low pressure cylinder, each having a piston, and inlet and discharge valve mechanisms for said cylinders, each of said valve mechanisms including a valve seat and a valve cooperating therewith and opened automatically by the pressure differentials created by the loaded operation of said compressor, and unloading means associated with corresponding valves on each cylinder for subjecting the sides thereof remote from their respective seats to pressures lower than those at their opposite sides to maintain said valves open to effect unloading.

10. In combination, a compound compressor having a high pressure cylinder and a low pressure cylinder, each having a piston, and inlet and discharge valve mechanisms for said cylinders, each of said valve mechanisms including a valve seat and a valve cooperating therewith and opened automatically by the pressure differentials created by the loaded operation of said compressor, and unloading means associated with a valve on each cylinder for subjecting the side thereof remote from its respective seat to a pressure lower than that at its opposite side to-main- -tain said valves open to effect unloading.

11. In a pump controlling system, a pump having a valve associated with one end .thereof and movable to open and close during each cycle of the pump end with which it is associated, andpump discharge pressure controlled vacuum governed unloading means associated with said valve for holding said valve open to effect unloading.

12. In a pump controlling system, a valve seat,

6 a a valve cooperating with said valve seat and movable to open position by a pressure-differential created during each cycle of loaded pump operation, and unloading means associated with said valve and including means forming a chamber to receive said valve in its open position, said unloading means also including means for subjecting the side of said valve more, remote from said seat continuously to a pressure less than the pressure which opens said valve, to hold said valve within said valve receiving chamber and so effect unloading.

13. In a pump controlling system, a cylinder, a piston, and valve mechanism including an inlet valve mechanism including a valve seat, a valve cooperating therewith and opened automatically by the pressure difierential created on suction strokes of said piston, and unloading means associated with said valve and including a guard formed with a recess to receive said valve in its open position, said unloading means also including means for subjecting the side of said valve remote from its seat to a vacuum.

, 14. In a pump controlling system, a cylinder,.a piston, and valve mechanism includinga discharge valve mechanism includinga valve seat, a valve cooperating therewith and opened automatically by the pressure differential created on discharge strokes of said piston, and unloading means associated with said valve for subjecting the side thereof remote from its seat to less than discharge pressure and for shielding the edges thereof from the flow of pressure fluid past the same.

15. In combination, a valve mechanism including a valve seat, a valve element cooperating with said seat, a valve seating spring, and a guard, said guard providing a recess for receiving said valve when the latter is .unseated to the maximum degree, and means associated with said recess for subjecting the side of said valve towards said recess to a subatmospheric pressure when said valve is in said recess.

16. In combination, a valve mechanism includlng a valve seat, a valve element cooperating with said seat, a valve seating spring, and a guard, said guard providing a recess for receiving said valve and a deeper recess for receiving said spring, and unloading means including means associated with said recesses for subjecting the side of said valve towards said first mentioned recess to a subatmospheric pressure when said valve is in said first mentioned recess.

1'7. In combination, a discharge valve mechanism including a valve seat, a valve element cooperating with said seat, a valve seating spring, and a guard, said guard providing a recess for receiving said valve, and unloading means including means associated with said recess for subjecting the side of said valve towards said recess to atmospheric pressure when said valve is in said recess. i

18. In combination, a discharge valve mechanism including a valve seat, a valve element cooperating with said seat, a valve seating spring,

and a guard, said guard providing a recess for receiving said valve, and unloading means includ-' said valve, a deeper recess for receiving said spring, and an intermediate recess, and means associated with said last mentioned recess for subjecting the side of said valve towards said recess to a subatmospheric pressure when said valve is in said first mentioned recess.

20. In combination, a valve mechanism including a valve seat, a valve element cooperating with said seat, a valve seating spring, and a guard, said guard providing a recess for receiving said valve, a deeper recess for receiving said spring, and an intermediate recess, and means associated with said last mentioned recess for vproducing therein a pressure less than the pressure whose flow said valve controls and for subjecting the sideof said valve towards said recess to such lower pressure, when said valve is in said first mentioned recess.

21. In a compressor controlling system, a compressor having valve mechanism including an inlet valve, means associated therewith for sub- Jecting said inlet valve to subatmospheric pressure conditions to maintain the same open to effect unloading, means for. creating a subatmospheric pressure during running of the compressor, and means for controlling the connection of said first mentioned means with said means for creating a subatmospheric pressure, controlled by compressor discharge pressure.

22. In a compressor controlling system, a compressor having valve mechanism including an inlet valve, means associated therewith for subjecting said inlet valve to subatmospheric pressure conditions to maintain the same open to effect unloading, a vacuum pump driven with the compressor for creating a subatmospheric pressure during running of the compressor, and means for controlling the connection of said first mentioned means with said vacuum pump, controlled by a narrower deeper annular groove having directly communicating therewith means for venting pressure from the space therein at the side of said valve opposite said valve seat to a lower pressure point, and a, still narrower and deeper annular groove to position a spring for pressing said valve toward said valve seat. 4

24. For use in a valve mechanism which in cludes an annular valve seat, a guard, a circular valve and an annular spring, a valve guard comprising a plate having a groove to receive a valve in a position with its outer surface fiush with the grooved face of said guard, a concentric narrower deeper groove having directly communicating therewith means for venting pressure from the space therein at the side of said valve opposite said valve seat to a lower pressure point, and a still narrower and deeper concentric groove to position a spring for pressing the valve toward the valve seat.

25. For use' in a valve mechanism which includes an annular'valve seat, a guard, a circular valve and an annular spring, a valve guard comprising a plate having a groove to receive an associated valve, a concentric narrower deeper groove having means directly associated therewith for venting pressure from the space therein at the side of said valve opposite said valve seat to a lower pressure point, and astill narrower and deeper concentric groove to position an asnism including a valve movable between a guard I and a seat during loaded pump operation, and means associated with said valve guard for subjecting the valve on one side thereof to the pressure of the fluid controlled by said valve to effect loaded pump operation, or to a lesser pres sure to effect unloaded pump operation.

27. In combination, in a pump, a valve mechanism including a valve movable between a guard valve on one side thereof to the pressure oi the fluid controlled by said valve to effect loaded pump operation, or to a lesser pressure to effect unloaded pump operation.

28; In combination, in a pump, a valve mechanism including a valve seat, a valve cooperating with said valve seat and movable to open position" by' a. pressure-differential created during each cycle of loaded pump operation, a valve guard having a chamber to receive'said valve in its open position, and means controlled by pump discharge pressure for automatically connecting said valve guard chamber to the pressure of the fluid controlled by said valve to permit normal operation oif said valve, or to a lesser pressure to hold said valve in said chamber and thereby etfect unloaded pump operation.

MARSHALL E, JENNINGS.

I CERTIFICATE OF CORRECTION. Patent No. 2,213,2h8. September 191m.

menu E. JENNINGS.

It is hereby certified that error appears in the printed specification of the abpve numbered patent requiring correction as follows: Page 6,- sec- 0nd column, line 58, claim' 211., after "guard" and before the comnia insert the words when said'valve i a'inepen poeition--; and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of "the case in the Patent Office.

Signed and sealed this-15th day or oetobelf, A. n. 191m.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

